Off with his head, part 2 -28 Jan 2017.

I ordered the necessary parts from Stein-Dinse in Germany on Sunday, arrived here in Wales on Wednesday. Even with the minimum postage cost it was still worth it as no one in the UK had all I needed in stock.

I did include base gaskets in my order so the next job was to lift the cylinder barrel. This gave me a chance to properly examine the bore. Unmarked and in good condition.

The pistons are fitted with four rings. Three above the gudgeon pin and one below. I knew early V7s were fitted with these but wasn’t sure if they kept on with this for all the 700s.

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I evened out the ring gaps out around the bore then replaced the base gasket. There is an oil drain hole in the face of the engine block. If the gasket is fitted upside down it will block the hole and the rocker box will fill with oil which can’t drain back to the sump. O-rings go on the two short studs (at 6 and 12 o’clock).

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Fitting the cylinder barrel isn’t difficult but can be a little hard on the fingers. First I turn the engine by the front crankshaft bolt until the piston is right at the top of its travel. I like to lightly oil the spigot of the cylinder which fits into the engine block as well as the bore itself. The barrel is dropped over the studs and the top of the piston started into the bore. There is a little chamfer at its lower end. This means that you can squeeze the top piston ring with your fingers until it goes into the chamfer. The cylinder should then slide further onto the piston till it meets the next ring. If it won’t go, don’t force it! Check the ring has gone into the chamfer. Repeat the procedure until all the rings have gone into the bore. The last one is the hardest because there’s not much finger space.

It’s now time for the head gasket. I think the gasket I’ve just removed was meant for a 750 as the bore is about 83mm whereas the new one (specific to the 700) has a bore of 80mm. Here the old is placed on top of the new and you can see the difference.

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The gasket was fitted but, before I put the cylinder head on I searched in the exhaust port for the old exhaust gasket. There should be a (squashed) copper ring in there. I scraped and picked at the port but couldn’t find the gasket. Now, I know that sometimes these can appear to be part of the head and hard to find so, I decided to get a second opinion. I measured the depth of the threaded section as 18mm and asked the members of the Yahoo Loopframe Group if anyone had a head they could check. Inside the hour I had a response from Charlie saying he had just measured a head and found the depth to be 17mm. I was right then. Someone had fitted the exhaust header without a gasket.

The design of this exhaust fitting means that, if the header becomes loose, it can vibrate in the port and damage the fine threads. There is some damage on this head but it’s still serviceable. A repair can be very expensive.

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Before putting the head on, I double-checked that the gasket was on the right way round. Again there is an oil drain hole which must line up with the hole in the barrel.

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The head was fitted on the studs then O-rings fitted to the four remaining (long) studs.

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The bracket for the rocker gear goes on next and the six nuts (five plus the sleeve-nut) can be torqued down in a diagonal sequence. I do;
– top right,
– bottom left,
– top left,
– bottom right,
– lower one by spark plug,
– top 10mm hex sleeve-nut.
The torque figure is 27.5 ft.lbs. This figure seemed a bit low to me and conflicted with the figure of 29 to 32 ft.lbs (4 to 4.5 Kg/m) given for later Guzzis. After taking advice fro members of the Loopframe Group, I’ll use 32ft.lbs in future.

Fit a new crush washer and refit the 26mm blanking plug over the sleeve-nut. Then refit the rocker gear. Drop the pushrods back where they came from. I like to turn the engine again to get the pushrods as low in the head as possible. Squeeze the relevant rocker, spring and washer back in place on the bracket and a bit of wiggling will allow you to get the spindle back in (screw hole at the top). Turn the spindle with a screwdriver until the locking screw can be refitted.

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Only ever use the original type and length of screw. It locks the shaft in place but mustn’t go too deep. The other side of the hole is an oil supply which then goes down the centre of the shaft and out again halfway along it to lubricate the rocker arm on the spindle. The wrong screw might restrict this oil flow.

At this point I refitted the exhaust header but now it does have an exhaust gasket. The threads of the exhaust nut were given a smear of copper grease.

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I didn’t do it up tight until I’d got the frame-to-header clamp in place in an effort to get everything lined up properly. I tighten up header nut, silencer clamp and frame-to-pipe clamp in that order.

The oil feed to the head was reconnected using the banjo bolt and new crush washers. I’m careful how I do this as the bolt is naturally fragile, being hollow with a cross-drilling. I use a short spanner.

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The inlet manifold and carburettor were refitted and the spark plug screwed back in. I’ve decided to repeat the job on the left hand cylinder so I’ve left adjusting the valve clearances for now. I put the rocker cover on with a couple of screws to keep the muck out for now.

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